JP6019420B2 - Arc welding control method and arc welding apparatus - Google Patents

Description

  The present disclosure relates to an arc welding control method and an arc welding apparatus that perform welding by generating an arc between a welding wire that is a consumable electrode and a base material that is a workpiece.

  FIG. 5 is a diagram showing an output waveform in a conventional arc welding control method involving a short circuit. The time change about welding current Aw, welding voltage Vw, and welding voltage command value Va is shown in order from the top. Hereinafter, a description will be given with reference to FIG.

  In FIG. 5, during the period from time t1 to time t2, an arc period in which an arc is generated between the welding wire and the base material, and during the period from time t2 to time t3, the welding wire and the base material are short-circuited. It is a short circuit period. In the arc period, welding is performed using a welding voltage command value Va reduced at a predetermined attenuation gradient for a predetermined time from the occurrence of an arc after a short circuit. As a result, the output voltage is reduced according to the welding voltage command value, so that even when the protruding length of the welding wire from the tip end of the tip is increased, the arc period is not increased and the state can be shifted to a short circuit state in a short time.

  Further, welding is performed by changing the predetermined time and the attenuation gradient according to welding current values having different numbers of short circuits. Thereby, since an output voltage falls according to a welding voltage command value, even when protrusion length becomes long, it can transfer to a short circuit state in a short time, without an arc period becoming long.

  As described above, in the arc period, stable welding can be performed even when the protrusion length becomes long by changing the attenuation gradient of the welding voltage command value and the predetermined time for applying the attenuation gradient according to the welding current. (For example, refer to Patent Document 1).

JP 2002-248573 A

  The arc welding control method of the present disclosure is an arc welding control method in which arc welding is performed by repeating a short-circuit period and an arc period, and an inductance value related to a welding output corresponds to a current region of the welding current during the arc period. And change. A predetermined time from the start of the arc period is the value of the first inductance, and after the lapse of the predetermined time, the voltage is controlled by changing to a second inductance value lower than the first inductance value. Is to change the inductance value a plurality of times.

  Further, the arc welding apparatus of the present disclosure is an arc welding apparatus that performs arc welding by repeating a short circuit period and an arc period, and the primary side rectification unit that rectifies input power and the output of the primary side rectification unit to AC The switching part to convert, the main transformation part which carries out pressure reduction of the output of a switching part, the secondary side rectification part and reactor which rectify the output of a main transformation part are provided. Furthermore, it detects whether it is in a short-circuit state or an arc state based on the output of the drive unit that controls the switching unit, the welding voltage detection unit that detects the welding voltage, the welding current detection unit that detects the welding current, and the welding voltage detection unit. A short-circuit / arc detection unit and a short-circuit control unit that controls the welding output during the short-circuit period based on the output of the short-circuit / arc detection unit. Furthermore, an arc control unit for controlling the welding output during the arc period based on the output of the short circuit / arc detection unit, a time measuring unit for measuring the elapsed time from the start of the arc period, and an electronic reactor control unit for controlling the inductance value And comprising. Then, during the arc period, the value of the inductance related to the welding output is changed corresponding to the current region of the welding current, and the predetermined time from the start of the arc period is the value of the first inductance, after the elapse of the predetermined time. The voltage control is performed by changing to a second inductance value lower than the first inductance value.

FIG. 1 is a diagram illustrating an output waveform obtained by the arc welding control method according to the first embodiment of the present disclosure. FIG. 2 is a diagram illustrating an output waveform obtained by the arc welding control method according to the first embodiment of the present disclosure. FIG. 3A is a diagram illustrating an arc length change by the arc welding control method according to the first embodiment of the present disclosure. FIG. 3B is a diagram showing a change in arc length by a conventional arc welding control method. FIG. 4 is a diagram illustrating a schematic configuration of the arc welding apparatus according to the first embodiment of the present disclosure. FIG. 5 is a diagram illustrating an output waveform obtained by a conventional arc welding control method.

  In the conventional arc welding control method, only the welding voltage command value is changed. Therefore, when the protruding length of the welding wire changes suddenly, the arc becomes unstable and it takes a long time to return to a stable state. Had problems. In addition, since the inductance value is determined by the reactor in the arc welding apparatus, it is difficult to stabilize the arc in the entire region from low current to high current.

(Embodiment 1)
Hereinafter, embodiments of the present disclosure will be described with reference to FIGS. 1 to 4.

  First, an arc welding apparatus that performs the arc welding control method of the present embodiment will be described with reference to FIG. FIG. 4 is a diagram showing a schematic configuration of the arc welding apparatus 21. The arc welding device 21 performs welding by repeating an arc state and a short-circuit state between the welding wire 17 that is a consumable electrode and the base material 20.

  The welding power source 15 of the arc welding apparatus 21 includes a main transformer 2, a primary rectifier 3, a switching unit 4, a reactor 5, a secondary rectifier 6, a welding current detector 7, and a welding voltage detection. Unit 8, short circuit / arc detection unit 9, and output control unit 10. The output control unit 10 includes a short circuit control unit 11 and an arc control unit 12. The arc control unit 12 includes an electronic reactor control unit 13 and a timer unit 14.

  The primary side rectification unit 3 rectifies the input voltage input from the input power source 1 outside the welding power source 15. The switching unit 4 controls the output of the primary side rectification unit 3 to an output suitable for welding. The main transformer 2 converts the output of the switching unit 4 into an output suitable for welding. The secondary side rectifier 6 rectifies the output of the main transformer 2. The reactor 5 smoothes the output of the secondary side rectification unit 6 to a current suitable for welding. The reactor 5 is a direct current reactor, and the inductance value is fixed. The welding current detector 7 detects the welding current. The welding voltage detector 8 detects the welding voltage. Based on the output of the welding voltage detection unit 8, the short circuit / arc detection unit 9 determines whether the welding state is a short circuit state in which the welding wire 17 and the base material 20 are short-circuited, or the welding wire 17 and the base material 20. It is determined whether or not the arc state in which the arc 19 is generated. The output control unit 10 outputs a control signal to the switching unit 4 to control the welding output. When the short-circuit control unit 11 determines that the short-circuit / arc detection unit 9 is in the short-circuit state, the short-circuit control unit 11 controls the short-circuit current that is the welding current during the short-circuit period. The arc control unit 12 controls the arc current, which is a welding current during the arc period, when the short circuit / arc detection unit 9 determines that the arc state is present. In addition, the arc control unit 12 includes an electronic reactor control unit 13 and a timer unit 14, and the number of times the inductance value is changed and the inductance value are determined by the electronic reactor controller 13, and the timer unit 14 outputs the inductance value. Time to do is decided.

  Further, the welding wire 17 is output in the direction of the base material 20 by the wire feed motor 16, is supplied with power via the tip 18, and an arc 19 is generated between the welding wire 17 and the base material 20 to perform welding. .

  Next, operation | movement of the arc welding apparatus 21 comprised as mentioned above is demonstrated using FIG. In FIG. 1, time t1 indicates the time when the arc is generated, time t2 indicates the time when the short circuit occurs, and time t3 indicates the time when the short circuit is opened and the arc is regenerated. A waveform indicated by a dotted line is a current waveform by conventional control. A period from time t1 to time t2 is an arc period Ta, and a period from time t2 to time t3 is a short circuit period. In the arc period Ta, voltage control is performed from the time when the arc is generated at time t1, and voltage control is continued during the period until the next short circuit occurs at time t2. During the short-circuit period from time t2 to time t3, the short-circuit control unit 11 supplies the welding wire 17 with a welding current for short-circuit opening that releases the state in which the welding wire 17 is short-circuited with the molten pool formed in the base material 20. Supply. Note that current control is performed during the short-circuit period.

  In FIG. 1, the control of the arc period Ta from time t1 to time t2 will be described. The period from time t1 to time t4 and the period from time t4 to time t2, which is the time when the next short circuit occurs, are controlled with different inductance values. As a result, especially during manual welding, there is a tendency for protrusions to occur and fluctuations in length are likely to occur, magnetic blows caused by sudden changes in the protrusion length of the welding wire 17 from the tip 18, the state of the base material 20, etc. Even when there is a disturbance, changes in the current waveform such as undershoot can be reduced, and arc welding resistant to the disturbance can be realized. Furthermore, since the current change is small and the short-circuit cycle is stable, the amount of spatter generated when the arc is disturbed can be reduced. In the case of conventional control, when the current during the arc period Ta undershoots, the time during the arc period Ta becomes longer, the droplets at the tip of the welding wire become larger, and a high current is required to release the short circuit. For this reason, the time of the short circuit period is also long, and the short circuit period is disturbed. The inductance value during the period from time t1 to time t4 is referred to as a first inductance, and the inductance value during the period from time t4 to time t2 is referred to as a second inductance. The time controlled by the first inductance between time t1 and time t4 is referred to as a first predetermined time. The inductance value is determined to be changeable by the electronic reactor control unit 13, and the predetermined time is determined by the timer unit 14.

  During the arc period, constant voltage control is performed by voltage control, spatter generation is suppressed by the first inductance in the first predetermined period during the period from time t1 to time t4, and the first predetermined time. During the period from time t4 to time t2 after the lapse of time, stable droplet formation and undershoot suppression are performed by the second inductance.

  Note that the short-circuit period is switched to the inductance in the short-circuit period, and current control is performed, so that the welding current flows at one or more constant increasing slopes toward the short-circuit opening so as to stabilize the droplet detachment and stabilize the short-circuit opening. Constant current control is performed to control the current.

  Further, the inductance value determined by the electronic reactor control unit may be controlled by a plurality of times of three or more as shown in FIG. In FIG. 2, control is performed with different inductance values in a period from time t5 to time t6, a period from time t6 to time t7, and a period from time t7 to time t8 when the next short circuit occurs. To do. As a result, the current can be gradually and stably reduced, and the change in current when a disturbance occurs is smaller, and a more stable arc can be realized than when controlling with two inductance values. Can do. The inductance value during the period from time t5 to time t6 is the first inductance, the inductance value during the period from time t6 to time t7 is the second inductance, and during the period from time t7 to time t8. The inductance value is referred to as a third inductance. The time controlled by the first inductance from time t5 to time t6 is called a first predetermined time, and the time controlled by the second inductance from time t6 to time t7 is called a second predetermined time. The inductance value is determined by the electronic reactor control unit 13, and the predetermined time is determined by the timer unit 14.

  The reason why the inductance value is controlled during the arc period will be described with reference to FIGS. 3A and 3B. 3A and 3B are diagrams showing changes in arc length (L1 to L3) when welding a base material 20 having a step. When the step is lowered, the protruding length of the welding wire 17 from the tip 18 changes, the arc becomes unstable, and it tends to take time to return to a stable state. FIG. 3A shows the result of arc welding control according to the present disclosure, and FIG. 3B shows the result of conventional arc welding control. The arc length before going down the step is set to L1, and the time until the arc length after going down the step returns to L1 is compared. Further, the time immediately after the step is lowered is Ta, and the subsequent time is Tb, Tc, and Td. Note that the time from time Ta to time Tb, the time from time Tb to time Tc, and the time from time Tc to time Td are the same. In FIG. 3A, the arc length at the point Ta immediately after going down the step increases from L1 to L2. Thereafter, the arc length returns from L2 to L1 at time Tb. The time taken at this time is T1. In FIG. 3B, the arc length at the time point Ta immediately after going down the step increases from L1 to L3. Thereafter, the arc length returns from L3 to L1 at time Td. The time taken at this time is T2. Note that the length of the arc length is longer in the order of L1 <L2 <L3. In this way, by changing the value of the inductance during the arc period, the change in the arc length immediately after the step is lowered can be reduced as compared with the conventional control. Can be reduced to about ３ until the original arc length is restored.

  The inductance value is determined by a table or formula depending on the setting current of the welding current or the set wire feed speed. Therefore, an appropriate inductance value must be set for each current region so as to correspond to the current region of the welding current. It is possible to set. For example, it is better to reduce the inductance value in a low current region of 150 A or less, and it is better to increase the inductance value in a high current region of 250 A or more. The value of the inductance is determined by experiment or the like. For example, in the arc period Ta, the value of the second inductance is controlled to be smaller than the value of the first inductance so as to gradually reduce the slope of the welding current waveform. .

  As described above, during the arc period, the inductance value related to the welding output is changed corresponding to the current region of the welding current, and the predetermined time from the start of the arc period is the first inductance value, and the predetermined time. After the elapse of time, voltage control is performed by changing to a second inductance value lower than the first inductance value, and the inductance value is changed a plurality of times during the arc period.

  In this way, a current change such as undershoot can be suppressed, and a stable arc state can be maintained even when the protruding length of the welding wire changes suddenly.

  The inductance value related to the welding output in the arc period Ta is an added value of the inductance value of the reactor 5 and the inductance value determined by the electronic reactor control unit.

  As described above, according to the arc welding control method and the arc welding apparatus of the present embodiment, the inductance value of the arc period is changed a plurality of times according to the current range. As a result, by changing the inductance value during the arc period, a stable arc state can be maintained even when the protruding length of the welding wire suddenly changes, and the arc is stabilized in the entire region. be able to.

  Further, it is possible to suppress a change in current such as undershoot when a disturbance occurs, to maintain a stable and constant cycle between the short-circuit period Ts and the arc period Ta, and to realize welding that is resistant to the disturbance and generates a small amount of spatter. Can do. Furthermore, since the inductance value can be selected according to the current range of the welding current, the arc stability can be enhanced in the entire current range from low current to high current.

  According to the present disclosure, by changing the inductance value during the arc period, it is possible to realize low spatter, improved arc stability, and a high-quality bead appearance, and a welding wire that is a consumable electrode and a welded electrode. The present invention is industrially useful as an arc welding control method and an arc welding apparatus that perform welding by generating an arc with a base material that is an object.

1 Input power supply 2 Main transformer (transformer)
DESCRIPTION OF SYMBOLS 3 Primary side rectification part 4 Switching part 5 Reactor 6 Secondary side rectification part 7 Welding current detection part 8 Welding voltage detection part 9 Short circuit / arc detection part 10 Output control part (drive part)
DESCRIPTION OF SYMBOLS 11 Short-circuit control part 12 Arc control part 13 Electronic reactor control part 14 Timekeeping part 15 Welding power supply 16 Wire feed motor 17 Welding wire 18 Tip 19 Arc 20 Base material 21 Arc welding apparatus

Claims (4)

An arc welding control method for performing arc welding by repeating a short circuit period and an arc period,
During the arc period, the value of the inductance related to the welding output is changed corresponding to the current region of the welding current, and the predetermined time is the first inductance value from the start of the arc period, and the elapse of the predetermined time After that, change the value of the second inductance lower than the first inductance value to perform voltage control,
An arc welding control method in which the inductance value is changed a plurality of times during the arc period.   The arc welding control method according to claim 1, wherein the inductance value is changed by electronic reactor control.   3. The arc welding control method according to claim 1, wherein the inductance value is a value obtained by adding an inductance value of a reactor of an arc welding apparatus and an inductance value of an electronic reactor. 4. An arc welding apparatus for performing arc welding by repeating a short circuit period and an arc period,
A primary side rectifier for rectifying the input power;
A switching unit for converting the output of the primary side rectification unit into alternating current;
A main transformer that steps down the output of the switching unit;
A secondary side rectifier and a reactor for rectifying the output of the main transformer, and
A drive unit for controlling the switching unit;
A welding voltage detector for detecting the welding voltage;
A welding current detector for detecting a welding current;
A short-circuit / arc detection unit for detecting whether a short-circuit state or an arc state based on the output of the welding voltage detection unit;
A short-circuit controller that controls the welding output during the short-circuit period based on the output of the short-circuit / arc detector;
An arc control unit for controlling the welding output of the arc period based on the output of the short circuit / arc detection unit;
A time measuring unit for measuring the elapsed time from the start of the arc period;
An electronic reactor control unit for controlling the value of the inductance,
During the arc period, the value of the inductance related to the welding output is changed corresponding to the current region of the welding current, and the predetermined time is the first inductance value from the start of the arc period, and the elapse of the predetermined time After that, an arc welding apparatus that performs voltage control by changing to a second inductance value lower than the first inductance value.

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